Light emitting diodes (LEDs) are increasingly employed as a basic lighting source in a variety of forms, including decorative lighting, for reasons among the following. First, as a device, LEDs have a very long lifespan, compared with common incandescent and fluorescent sources, with typical LED lifespan at least 100,000 hours. Second, LEDs have several favorable physical properties, including ruggedness, cool operation, and ability to operate under wide temperature variations. Third, LEDs are currently available in all primary and several secondary colors, as well as in a “white” form employing a blue source and phosphors. Fourth, with newer doping techniques, LEDs are becoming increasingly efficient, and colored LED sources currently available may consume an order of magnitude less power than incandescent bulbs of equivalent light output. Moreover, with expanding applications and resulting larger volume demand, as well as with new manufacturing techniques, LEDs are increasingly cost effective.
Various LED light strings have been proposed for decorative illumination purposes. Most LED light sets and rope lights, including flat rope lights come with a variety of lighting options. Most are rotating color combinations or have the ability to change colors as desired, within a limit. Those LED light sets where colors can be programmed or selected by the user, have the entire set change to any one color at a time. One example of this is commonly referred to as a dual colored light string. This type of LED light string takes advantage of the fact that LEDs only illuminate when a voltage is applied in the correct direction. By coupling two LEDs together in parallel, anode to cathode and cathode to anode, so that only one of the LEDs will light with each voltage polarity, a dual color light string can be created. This type of light string may emit white light when a positive voltage is applied and multi-colored light when a negative voltage is applied. While multiple variations of this kind of dual-polarity LED light string are known, such LED light strings are not capable of placing different combinations of LEDs on the light string in specific locations to be energized in a forward and reverse bias as selected by a controller.
Exemplary LED-based light strings are described in the literature which employ purely parallel wiring of discrete LED lamps using a step-down transformer and rectifier power conversion scheme. The LED light string descriptions found in the prior art convert input electrical power, usually assumed to be the common U.S. household power of 110 VAC to a low voltage, nearly DC input.
Thus, conventional LED light string controllers are lacking in certain aspects. In particular, none of the prior art LED light string controllers disclose an LED light string that includes different combinations of LEDs on a light string in specific locations, under control of a controller that can easily and conveniently select a plurality of LED light display patterns that correspond to pre-arranged lighting color schemes applicable to holidays and other events.
Conventional flat rope systems lack in one additional aspect. Namely, these conventional systems utilize three LEDs in parallel where all of the LEDs change to the same color at the same time and do not have the capability to dynamically change the display pattern over in accordance with pre-programmed event patterns.